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Archive for the 'Crop improvement' Category

Estimation of general combining ability (GCA) and prediction of hybrid performance

1.      Field design If you want to use the block effect for adjustment, be sure that hybrids with the same female are not grown in the same block, otherwise you will correct for the effect of the females. As such the randomization has to be done for the females. For example in each block 14 [...]

December 11th, 2013
Topic: Crop Science, Plant breeding Tags: None

Increasing selection gain for the target environment

1. What is the selection and the target environment The selection environment is usually managed by the breeder with regard to field design, soil homogeneity and fertilizer application. The selection environment can include managed trials genotypes are grown under a clearly defined stress. The target environment is the set of fields and future seasons in which [...]

December 3rd, 2013
Topic: Crop Science, Plant breeding Tags: None

Some general advice for implementing genomic selection into a breeding program

General procedure to conduct genomic selection Decide which trait should be predicted. Is it a quantitative (like yield) or qualitative trait (like a disease). If it is a quantitative trait you may need multi-year phenotypic data with a moderate to high heritability (h² > 0.4) and a large set of genotypes (n > 200). If [...]

November 4th, 2013
Topic: Plant breeding Tags: None

Line development and hybrid evaluation (example maize)

Line development and testing within the heterotic pools Source population Open-pollinated cultivars, synthetic cultivars, single crosses, back-crosses, dou- ble crosses, related line crosses, and exotic germplasm can be used as source population. The requirements for source material in hybrid breeding are a high performance level and broad genetic variation for all agronomically important traits such [...]

April 6th, 2013
Topic: Crop Science, Plant breeding Tags: None

Estimates of genetic correlation between two traits / one trait in two selection environments

For estimating selection efficiency, an estimate of the genetic correlation has to be given. This value can be estimated using different equations and/or models: Based on the phenotypic correlation between two traits or the same trait estimated in different environments: (Falconer and Mackay, 1996): where is the phenotypic correlation between trait 1 and 2 and [...]

February 10th, 2013
Topic: Plant breeding Tags: None

Statistical methods to analyze large spectral data sets

Spectral indices Spectral indices are developed on the basis of ratios or differences in the reflectance at given wavelengths. Those wavelengths are related to certain performance traits such as biomass production, plant water content and photosynthesis (for further detail see the article about spectral reflectance indices). Advantages: Cheap devices can be developed to measure the [...]

December 27th, 2012
Topic: Crop Science, Plant breeding Tags: None

Secondary traits for maize grain yield under drought stress conditions

1         Importance of secondary traits of maize under drought stress Drought can affect maize production by decreasing plant stand during the seedling stage, by decreasing leaf area development and photosynthesis rate during the pre-flowering period, by decreasing ear and kernel set during flowering, and by decreasing photosynthesis and inducing early leaf senescence during grain-filling. Additional [...]

December 23rd, 2012
Topic: Crop Science, Plant breeding Tags: None

Genotype-by-environment interactions (GxE)

Genotype x environment (GxE) interaction occurs when different genotypes respond differently to different environments. GxE varies with the material tested and the sites chosen for testing (Darbeshwar 2000). Especially complex inherited, quantitative traits are influenced by environmental effects. As with breeding only the genetic effect can be modified the ratio of the genetic effect within [...]

June 24th, 2012
Topic: Crop Science, Plant breeding Tags: None

Spectral reflectance indices

Leaf pigments absorb light strongly in the photosynthetic active radiation region (PAR, 400-700 nm) but not in the near infrared region (NIR), thus reducing the reflection of PAR but not of NIR (700-1200 nm) (Araus et al. 2001). Such a pattern of pigment absorption determines the characteristic reflectance signature of leaves. While leaf reflectance is [...]

June 5th, 2012
Topic: Crop Science, Plant breeding Tags: None

Breeding maize with high amylose content

Genotypic material High-amylopectin corn Waxy corn contains only amylopectin and no amylase starch molecule in opposition to normal dent maize varieties that contain both. Amylopectin or waxy starch is mainly used in food products, but also in the textile, adhesive, corrugating and paper industry. Amylopectin or waxy cornstarch is relatively easy to gelatinise, produces a [...]

April 29th, 2012
Topic: Crop Science, Plant breeding Tags: None